The Mass Spectrometry Shared Facility is a shared resource for investigators in the Comprehensive Cancer Center. This Shared Facility has two PE-Biosystems/PE-Sciex mass spectrometers, a PE-Sciex API III triple quadrupole instrument and a Voyager Elite MALDI-TOF instrument. Both instruments were obtained using NIH/NCRR Shared Instrumentation Grants. The Shared Facility provides the following services to the Comprehensive Cancer Center investigators for their federally funded research: 1) support of drug metabolism- pharmacokinetics projects by the development of HPLC mass spectrometry-based drug analyses; 2) quality control assurance of peptides synthesized in the Peptide Synthesis and Analysis Shared Facility; 3) the determination, with high fidelity, of the molecular weights of macromolecules including proteins, oligonucleotides and carbohydrates; 4) identification and sequence analysis of peptides and modified peptides (e.g., phosphopeptides) isolated from biological matrices and from protease digestion of pure proteins; 5) development of high sensitivity methods for the separation and analysis of peptides, in particular those based on capillary electrophoresis-MS and-MSMS; 6) consultative support of individual investigators so that they modify their analytical methods in order to utilize the full benefits of mass spectrometry; and 7) provision of a teaching program in mass spectrometry, including a course for graduate students, postdoctoral fellows and faculty, and extramural speakers with expertise in particular areas of mass spectrometry. The staff of the Shared Facility consists of the Director and the operators of the two mass spectrometers.